Process for the preparation of arylides of 2, 3-hydroxy-naphthoic acid



Patented Dec. 6, 1932 S ATENT @Flf'lfih JOHN M. TENKER AND LOUISSFIEGLER, OF SOUTH MILWAUKEE, WISCONSIN, ASSIGNOBS TO 3:. EU FONT DENEIIEGUES Ga CGMPAZIY, OF WZLMINGTON, DELAVJARE, A COR- PQRATEON 0FDELAW'ABE PROCESS FOR No Drawing.

This invention relates to intermediates for a-zo dyestuffs. Moreparticularly, this invention deals with a novel, improved process forpreparing arylides of 2,3-hydroXy-naphthoic acid. The latter compoundsare useful in the of preparing azo pigments water-i solubleazo-dyestuiis or of developing azo dyestuffs upon t stile fiber. Ineither procedure arylides of 2,3-hydroXy-naphthoic aci are used ascoupling components for con bination with various aryl-diazo compounds.The arylides of 2,3-hydro: y-naphthoic acid have heretofore beengenerally prepared by reacting 2,3-hydroxy-naphthoic acid with thecorresponding desirable aryl-amine in an inert solvent, such as benzene,toluene, or Xylene, in the presence of a dehydrating agent such asphosphorus trichloride, phosphorus org-chloride or thloiyl chloride.This method, although fairly satisfactory for the aryla1nines of lowmolecular weight, such as aniline, gives highly unsatisfactory resultswhen used with aryl-amines of higher molecular weight, such as 06- or,B-naphthylamine, anisidine, or nitroaniline. As a rule, the product inthe latter cases contains a considerable amount of impurities which dullthe shade of the ultimate oyestufi'. Moreover, the reaction is a verydelicate one, and 7 very special precautions must be selected for eachind vidual case to obtain an intermeoiate of high purity and givingsatisfactory brlll'ance of shade.

We have now made the surprising discovery that. if instead of using thearyl-amine base in the above procedure, the same is replaced by a halideof the aryl-amine, for in stance, the hydrochloride, the reactionproceeds with unusual smoothness and reg larly produces. in high yield,a product of greater purity than obtained by previous methods. Thedyestufis ultimately prepared from the intermediates thus formedsimilarly erhibif greater brilliance. due to the purity of saidintermediates. These improvements result,

Application filed. November 18, 1931.

THE PBEEAEATION AEYLIDES OF 2,3-HYDROXY-NAPHTHOIC ACID Serial No.575,484.

no matter what the aryl-amine is that is being used, whether of high orlow molecular weight; whether unsubstituted by groups other than theamine, or substituted by various groups, such as allroxy, halogen, nitroand the like. Moreover, the use of aryl-amine salts renders the entirereaction uniform for aractically all aryl-amines. This is an advantageof great importance in practice since it enables the preparation of anumber of various arylides of 2,S-hydroxy-naphthoic acid with but asingle set of apparatus.

Other incidental advantages now from the election of an aryl-amne halidein lieu of aryl-amine base for the reaction. One of these is the factthat the hydrochloride of an aryl-amineis in many cases easier toprepare and isolate in pure form than the base. In fact, in the case ofmany aryl-amines, the hydrochloride is always prepared first, and thebase is then prepared therefrom by treatment with aqueous alkali andseparation from the resulting aqueous sa t solution.

Another advantage is that it is easier to dehydrate the reaction mixturewhere a salt of the aryl-amine'is employed. Q

oince the entire reaction isone of splitting off water by means ofphosphorus trichloride, or the like, it is obvious that the reactantsmust initially be as free from water as possible. Now where thearyl-amine is used in the form of a salt, it is relatively easy to getrid of the final races of moisture by partially evaporating he reactionmixture prior to the introduction of phosphorus trichloride. In thecase, however, where the free ba e is employed, this procedure isfrequently not feasible, sincethe aryl-amine tends to evaporate togetherwith the inert solvent. It therefore becomes necessary in'such cases toresort to costly and laborious drying procedures.

Still another advantage of our novel procedure is that the reaction isless violent, and that all the phosphorus trichloride may be added atonce at the beginning of the reaction. 90

In the old procedure such a course was frequently impossible, due to theviolence of the reaction. The dehydrating agent, therefore,

had to be fed in gradually and with extreme care. This not only wouldincrease the cost of labor, but would spread poisonous fumes into thesurrounding atmosphere.

It is accordingly an object of our invention to improve the process ofpreparing arylides of 2,3-hydroxy-naphthoic acid whereby to improve thepurity of the final product, to make the reaction more smooth andcontrollable, to make the reaction applicable uniformly to a great manyaryl-amines including amines of high molecular weight, and in general toendow the process with the many and various advantageous improvementsabove enumerated or indicated.

\Vithout limiting our invention to any specific procedure, the followingexamples are given to illustrate our preferred mode of carrying out thesame. Parts given are parts by weight.

' Example 1 100 parts of a-naphthylamine are dissolved in 1400 parts ofa hydrocarbon mixture having a reflux temperature of 9895 0., forinstance, a mixture consisting of 650 parts of benzene and 750 parts oftoluene. 8 parts of 20 B. hydrochloric acid are added and the mixture ispartially distilled until it is anhydrous, fresh dry solvent beingcontinually introduced to compensate for the solvent distilled off. Themixture is nowcooled to 60 (1., and 131 parts of 2,3-hydroxy-naphthoicacid are added. 37.8 parts of phosphorus trichloride are now introducedand the mass is gradually heated to reflux within a period of 6 to 7hours and then further kept at reflux temperature for about 15 hours.During this procedure hydrochloric acid is evolved and may be recoveredfor reuse in a subiequent batch. The mass is now cooled to about 7 5 0.,diluted with water and distilled until free of solvent. (The latter maybe collected and reused directly for a subsequent batch, without anyintermediate drying step.) The residual mass is filtered and washed withhot water until free of mineral acid. The filter cake contains thea-naphthalide of 2,3-hydroxy-naphthoic acid in high yield.

Example 2 drocarbon portions of the distillate being returned to theoriginal mass. The mixture is now cooled to 60 C. 118 parts of2,3-hydroxy-naphthoic acid and 33.5 parts of phosphorus trichloride arenow added, and the procedure continued as in Example 1.

The final product contains the para-anisidide of 2,3-hydroxy-naphthoicacid in high yield.

In a similar manner many other arylides of 2,3-hydroxy-naphthoic acidmay be prepared with great efficiency. Among the various aryl-aminesactually tried by us for the above purpose, the folowing may bementioned:

aniline I o-toluidine m-toluidine m-nitraniline p-nitraniline It shouldbe understood that our invention is not limited to the precise detailsabove disclosed, but is susceptible to many variations and modificationsas will be readily understood to those skilled in the art.

We claim:

1. In the process of preparing an arylide of 2,3-hydroxy-naphthoic acidby reacting 2,3-hydroxy-naphthoic acid with an arylamine, the step ofemploying the latter reactant in the form of a halogen acid saltthereof. 7

2. In the process of preparing an arylide of 2,3-hydroxy-naphthoic acidby reacting 2,3-hydroxy-naphthoic acid with an arylamine, the step ofemploying the latter reactant in the form of its hydrochloric acid salt.

3. The process of preparing an arylide of 2,3-hydroxy-naphthoic acidwhich comprises reacting o2,3-hydroxy-naphthoic acid with the halogenacid salt of an aryl-amine in an inert solvent and in the presence of adehydrating agent.

4. The process of preparing an arylide of 2,3-hydroxy-naphthoic acidwhich comprises reacting 2,3-hydroxy-naphthoic acid with thehydrochloride of an aryl-amine in an inert 2,5-dimethoxy-anilinea-naphthylamine B-naphthylamine o-anisidine p-anisidine solvent and inthe presence of phosphorus trichloride.

5. The process of preparing an arylide of 2,3-hydroxy-naphthoic acidwhich comprises effect ng a mixture of a halogen acid salt of anaryl-amine with an inert organic liquid, partially evaporating themixture to remove traces of moisture, adding 2,8-hydroxynaphthoic acidand a dehydrating agent, and heating the mass to reflux until reactionis complete.

6. The process of preparing an arylide of 2,3-hydroxy-naphthoic acidwhich comprises effecting a mixture of a hydrochloride of an aryl-aminewith an inert organic liquid, partially evaporating the mixture toremove traces of moisture, adding 2,8-hydroxynaphtho c acid andphosphorus trichloride and heating the mass to refluxuntil reaction iscomplete.

In testimony whereof we afiix our signatures.

JOHN M. TINKER. LOUIS SPIEGLER.

